Section 7 Reproduction and Inheritance Flashcards
1
Q
what are genes?
A
chemical instructions that code for a particular protein determine inherited characteristics
2
Q
Describe DNA
A
double helix, two strands coiled together held together by bases (A-T,C-G) type of nucleic acid
3
Q
Describe mitosis
A
used for asexual reproduction produces identical cells splits to form two cells makes new cells for growth and repair
4
Q
where does asexual reproduction happen?
A
plants and bacteria
5
Q
describe meiosis
A
1.duplicates DNA, pairs line up 2. pairs pulled apart, each cell has one copy 3. line up again and pulled apart 4 genetaclly different haploid gametes are produced
6
Q
what is pollination?
A
transfer of pollen from an anther to a stigma
7
Q
How is a plant adapted for insect pollination?
A
Brightly coloured to attract insects Scented to attract insects Sticky pollen grains to attach to the insect Sticky stigma to rub against the insect Stamens enclosed in flower
8
Q
How is a plant adapted for wind pollination?
A
Small petals No nectar Lots of pollen grains that are large and smooth to help float through the air Long filaments so that anthers hang outside of flower when ripe Large feathery stigma that hang outside the flower to catch pollen
9
Q
how is a plant fertilised?
A
1.pollen lands on the stigma 2.pollen tube grows down through the style to the ovary 3.nuclei fuse together to make a zygote then divide to make an embryo fertilised gametes form a seed
10
Q
give an example of a natural and artificial example of asexual reproduction in plants?
A
natural - runners, strawberry artificial - take cuttings
11
Q
What is the function of the testis in males?
A
- produce sperm - produce testosterone - are suspended to keep cool below body temperature so sperm are not killed.
12
Q
what does testosterone cause?
A
extra hair muscles sperm production deeper voice penis and testicle enlarge
13
Q
what does oestrogen cause?
A
extra hair wide hips breasts ovum release
14
Q
how often is a ovum produced?
A
every 28 days
15
Q
what happens if the ovum is not fertilised?
A
breakup and pass out with the lining
16
Q
what does the ovum attach to when it is fertilised?
A
endometrium
17
Q
what happens in the menstrual cycle on day1 day 4 - 14 day 14 - 18
A
day 1 - bleeding starts day 4 - 14 uterus builds up day 14 - day 28 wall is maintained
18
Q
What are the roles of Oestrogen and Progesterone in the menstrual cycle?
A
oestrogen - Repairs uterus lining, inhibits (shuts down) FSH production, stimulates LH production.
progesterone - maintains uterus lining, inhibits FSH production, inhibits LH production.
19
Q
which sex contains a y chromosome?
A
males
20
Q
give examples of environmental variation in humans?
A
lifestyle on health intelligence from school weight
21
Q
give examples of environmental variation in plants?
A
sunlight moisture minerals temperature
22
Q
what is the theory of evolution?
A
life began as simple organisms from which more complex organisms have evolved
23
Q
what is natural selection or survival of the fittest?
A
individuals who can survive better by competing for resources reproduce more and each generation is better adapted
24
Q
what is a mutations?
A
random change in DNA that can be inherited e.g. stop production of a protein different protein is produced
25
how can mutations be harmful?
in reproductive cells offspring might develop abnormal or die cancer- mutation in body cells which invade
26
how can bacteria become antibiotic-resistant?
mutations mean the bacterium is less affected live for longer and reproduce - gene is passed on
27
What is germination?
When a seed starts to grow
28
What conditions do seeds need to start germinating?
Water - activate enzymes that break down food Oxygen - for respiration Temperature - suitable for seeds to work
29
What are the steps to seed germination?
The seeds take in the water and it starts to grow using its store of energy The first root starts to grow down into the soil The shoot grows up Extra roots grow and the first green leaves appear
30
Where do germinating seeds get energy from?
When a seed starts to germinate it gets glucose for respiration from its own food store giving energy it needs to grow Once got leaves it gets its energy from photosynthesis
31
What does the amniotic fluid do?
The amnion membrane forms Surround the embryo and is full of amniotic glue which protects against knocks and bumps
32
How can the chance of mutation be increased?
Being exposed to ionising radiation and chemicals called mutagens
33
Explain the water cycle
Heat from the sun makes water evaporate from land and sea turning to water vapour and also from transpiration When the water vapour rises it cools and condenses to form clouds Water falls through the clods as precipitation
34
How much nitrogen is in the atmosphere?
78%
35
What is nitrogen needed for?
Making proteins for growth
36
What is the function of a pubic bone in males?
Forms part of the pelvic girdle.
37
What is the function of the bladder?
Stores urine which is produced in kidneys, released at intervals from body via urethra.
38
What is the function of the prostate gland in males?
- where the vas deferents join the urethra. - produces semen, fluid in which sperm swim.
39
What is the function of the scrotum in males?
A sack of skin that holds the testis outside the abdominal cavity.
40
What is the function of the urethra in males?
Carries urine or sperm from the body.
41
What is the function of the penis in males?
- Contains erectile tissue - introduces sperm into the vagina during sexual intercourse. - sperm are carried along urethra during ejaculation.
42
What is the function of the vas deferens in males?
- tube that stores sperm before ejaculation which are then passed along with semen produced by the seminal vesicles and prostate gland, into the urethra.
43
What is the function of the ovary in females?
- site of egg and hormone production as part of menstrual cycle. - produces oestrogen and progesterone.
44
What is the function of the oviduct / Fallopian tube in females?
- carries egg released by ovary to uterus. - can take 2-4 days - lining of oviduct has ciliated cells. - fertilisation happens here.
45
What is the function of the uterus in females?
- Early development occurs here. - inner lining of uterus is called endometrium. - outer lining of uterus is called myometrium which is muscle and elastic tissue so able to stretch when baby grows.
46
What is the function of the cervix in females?
- entrance to the uterus, through which sperm must swim to fertilise an egg.
47
What is the function of the lining of the uterus in females?
- provides site for the development of a placenta. - allows blood of developing embryo to exchange materials with mothers blood. - in non-pregnant women, lining is shed (periods) every month as part of menstrual cycle and new one is made every month.
48
What is a gonad?
The sexual part of an animal that produces gametes. In males: gonad produces sperm. In females: gonad produces ovary.
49
Describe the differences between sexual and asexual reproduction.
Sexual: - 2 parents (female and male) - each produce gametes (sex cells) - creates new, unique individual Asexual: - 1 parent - no gametes involved - reproduction by mitosis (cell division) - creates a clone of parent (not unique, same genes)
50
What happens during fertilisation?
- head of spermicide releases enzymes to digest a path through protective layer surrounding the egg. - sperm passes through the egg cell membrane. - egg immediately releases a thick layer of material to prevent entry of any more sperm cells. - the 23 chromosomes in the egg join and fuse with the 23 chromosomes in the sperm to form a diploid zygote which carries 46 chromosomes and will undergo cell division and develop into an embryo.
51
Describe the structure of an insect pollinated flower.
Petals Anther Filament Stigma Style Ovary Ovules Nectary Sepal Anther + filament = stamen (male part) Stigma + style + ovary = carpel (female part).
52
Describe the structure of a wind pollinated flower.
Petals / sepals Stigma Style Ovary containing ovules Filament Anther
53
What does the growth of the pollen tube followed by fertilisation lead to?
Seed and fruit formation: - ovule becomes a seed - ovary becomes a fruit - ovule wall becomes testa - inside testa is the embryonic plant, contains a small root (radicle) and a small shoot (plumule) and a food store for when plant starts to grow - ovary wall becomes the fruit coat.
54
Describe the structure of an insect pollinated flower.
55
Recall the structure of the female reproductive system.
56
Recall the structure of the male reproductive system.
57
How is the developing embryo protected by amniotic fluid?
The amniotic fluid helps to cushion the baby from bumps and injury, as well as providing them with fluids that they can breathe and swallow. It also helps the baby's musculoskeletal system to develop and maintains a constant temperature for the baby.
58
Describe the role of the placenta in the nutrition of the developing embryo.
The placenta plays a vital role in providing the fetus with nutrients and disposing of waste products created by the fetus. These substances pass to and from the fetus via diffusion between the mothers and baby's bloodstream in the placenta, including oxygen, nutrients and metabolic waste (urea and carbon dioxide). The blood of the mother and fetus do not come in contact, but substances diffuse between the two.
59
Recall the roles of oestrogen and testosterone in the development of secondary sexual characteristics in puberty.
Oestrogen (females):
- causes voice box to remain small
- greater proportion of body becomes fat rather than muscle - provides supply of nutrients during pregnancy
- pelvis enlarges so hips widen - allows passage of baby through pelvic girdle during birth
- breasts grow with fat deposits - provide milk for the baby
- menstrual cycle begins - eggs are released by the ovaries each month.
- hair develops on pubic region and under arms.
Testosterone (males):
- greater proportion of body becomes muscles rather than fat
- no development of breasts
- sperm production starts
- hair develops on pubic region and under arms as well as face
- pelvis remains narrow - helps with fast running
- voice box grows larger - gives lower pitch voice and voice 'breaks'.
60
What does the nucleus of a cell contain?
Chromosomes on which genes are located.
61
What is a gene?
A section of a molecule of DNA that codes for a particular protein.
62
What is a DNA molecule?
63
What are different versions of genes called and what do they do?
Called alleles, alleles come in pairs, if both are the same then person is homozygous, but if both are different then person is heterozygous.
64
What is the diploid number of chromosomes and the haploid number of chromosomes in human cells?
Diploid: 46
Haploid: 23
65
What is a monohybrid cross?
When two organisms with the same genotype so are bred together to look at one characteristic.
66
What are the probabilities of outcomes of monohybrid crosses?
Will always give 3:1 ratios.
67
What is the sex of a person controlled by?
One pair of chromosomes. The egg from the mother always contains an X chromosome. If female the sperm from father that fertilised mothers egg also contained X chromosome, giving XX chromosomes for child = female. If male, sperm from father that fertilised mothers egg contained a Y chromosome, giving XY chromosomes for child = male.
68
What does random fertilisation produce?
Genetic variation of offspring.
69
What can variation within a species depend on?
Variations of humans can be caused by genes, environment or both.
e.g. Variation caused by genes: eye colour, tongue rolling, blood group.
Variation caused by the environment: accents, scars, languages, piercings / tattoos.
Variation caused by both: skin colour, height, weight.
70
What is mutation?
A change in the order of bases in DNA or a change in the number of chromosomes, that can be inherited. (Caused by insertion, deletion or substitution).
71
Are mutations beneficial or harmful?
Some mutations are neutral - but cause no effect.
Many mutations are harmful.
A small number of mutations are beneficial. (This is the basis of evolution).
72
How can mutations be increased?
By exposure to radiation and some chemical mutagens.
73
Describe evolution by natural selection.
1) living things show variation and are not all the same.
2) resources living things need to survive are limited and so they must compete for them, only some will live.
3) some varieties of a species have a better chance of survival, so they have more chance of breeding and pass their higher chances on in their genes.
4) means a greater proportion of individuals in next generation have the better alleles and so have better characteristics to have better chance of survival too.
5) species become better and better able to survive. 'Best' features are naturally selected and species becomes more adapted to environment.
74
What is bacterial resistance to antibiotics and what are the effects?
Bacteria sometimes develop random mutations too, meaning their characteristics may change and this could lead to them being less affected by a particular antibiotic.
This leads to an increase in bacterial populations, as the bacteria live for longer and reproduce many more times.
this increase can lead to infections being difficult to control as the gene is passed down to the offspring.
75
How can plants with desired characteristics be developed?
Selective breeding or Artificial selection.
This can also occur in animals e.g. All dogs evolved from wolves, but over millions of years different desired characteristics were identified and were bred thousands of times (each time using puppies with most prominent desired characteristics) over thousands of generations to create all different breeds we have today.
76
What is codominance?
Two alleles which are both expressed equally in the phenotype of an organism (one is not dominant over the other).
77
What is the artificial selection method?
- Desired characteristics are identified.
- Breed them together.
- Offspring with most prominent desired characteristics then bred together.
- repeated over several generations to create all different breeds of dogs from greyhounds to chihuahuas.
78
What is a genotype?
The genetic make up of an organism concerning the alleles of a particular gene.
79
What is meant by the term recessive?
Alleles that are only noticed in the absence of the dominant allele.
80
What is meant by the term dominant?
Alleles that are always noticed if they are present.
81
What are phenotypes?
Physical characteristics.
82
What is meant by the term heterozygous?
When a persons pair of alleles are different.
83
